Chancellor Angela Merkel warned on Monday that global warming will accelerate at a dramatic rate unless leaders reach a deal on limiting greenhouse gas emissions as soon as possible.

After marathon talks in Durban last December, countries agreed to forge a new deal by 2015 that would for the first time force all the biggest polluters to limit greenhouse gas emissions.

Critics said at the time, however, the plan was too timid to slow global warming.

"Time is of the essence," Merkel told an international conference in Berlin, where delegates from more than 30 countries are preparing for a major UN climate conference at the end of the year in Qatar.

Attendees are discussing how to prevent global temperatures from rising more than 2 degrees Celsius.

Merkel's comments came a day after Germany's Environment Minister questioned the country's ability to reach its own climate goals, in an interview with newspaper Bild am Sonntag.

These include introducing 1 million electric cars and reducing energy usage 10 percent by 2020. As of the beginning of 2012, only 4,541 electric cars were in use, according to the German Federal Motor Transport Authority.